I've attached a picture showing some white stains that we have on our blue ceramic tile around our spa spillover. We've only owned the house for a couple of months, so we have no idea how long these stains have been there. Our water is very high in CH because the previous owner's pool service used cal-hypo once a week to shock. Since we've owned the pool, we've put nothing in the water except bleach and some muriatic acid. What's odd is that these stains appear where the water doesn't make contact with the tile. Any ideas what these stains could be from, and how to remove them without affecting our nice clear water?